Thermomechanical analysis of tungsten-copper joints for fusion applications using digital image correlation

Abstract
The European DEMOnstration Fusion Power Plant DEMO represents a significant milestone in the progression towards sustainable fusion energy and a critical phase between ITER and commercial fusion reactors, aiming to demonstrate sustained net positive electricity production. Thanks to its properties, tungsten is a promising material for divertor armor. Coupled with copper alloys as heatsinks, they offer robust thermal management properties to deal with intense thermomechanical loads and irradiation damage. Understanding the thermomechanical behaviour of tungsten-copper joints during their application is then necessary for divertor design.

This study presents experimental analysis on tungsten-copper brazed materials subjected to thermomechanical solicitations to simulate mono-block conditions with heat fluxes expected to reach 20 MW/m2 and so to face potential creep-fatigue failure. The experimental tests were coupled with Digital Image Correlation up to 400 °C to analyse the thermomechanical behaviour of these joints, providing insights into their thermal behaviour, structural integrity, damage accumulation, joint failure and identification of strains required for creep-fatigue assessment using design codes.